Figure 3. Pattern analysis of serotonin-positive cells in the inner
retina of an adult zebrafish

Analysis of the pattern of serotonin-positive cells in the inner
retina of an adult zebrafish, illustrating pattern characteristics that
are common for inner retinal cells of various types. A, Nearest neighbor
distance (NND) distribution, as a function of the fraction of cells
within the analyzed sample. Note how the distribution is well estimated
by a normal (Gaussian) function (red line), consistent with a non-random
distribution of points. Conformity ratio analysis of the NND
distribution [17] also reveals the two-dimensional pattern to be
non-random. B, Density recovery profile (DRP) [60] analysis of the same
pattern of serotonin-positive cells. Each serotonin-positive soma
(abscissa value 0) is surrounded by a two-dimensional area that is
devoid of other serotonin-positive somata (i.e., the density values
equal zero below 30 μm). The density of the sample (black horizontal
line) is not "recovered" until an annular area approximately 60 μm
away from each soma is sampled. The recovered density thereafter
approximates the density of the entire sample.